Internal-combustion engines – Combustion chamber means having fuel injection only – Using multiple injectors or injections
Reexamination Certificate
2000-05-23
2001-02-27
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Using multiple injectors or injections
C123S506000
Reexamination Certificate
active
06192856
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic fuel injection apparatus, and in particular to an electronic fuel injection apparatus which controls a distribution (VE)-type fuel injection pump for a diesel engine.
2. Description of the Related Art
A control circuit of an electromagnetic spill valve (SPV) of a distribution-type fuel injection pump provided for adjusting a fuel injection quantity of a diesel engine in a conventional electronic fuel injection apparatus increases the fuel injection quantity to abnormally raise an engine revolution (RPM), resulting in a dangerous state when a fault occurs in the electromagnetic spill valve and the control circuit thereof.
On the other hand, when the solenoid driving current of the electromagnetic spill valve supplied by the control circuit presents an abnormal state as in the Japanese Patent Publication Laid-open No.7-269404, the abnormal state is detected by monitoring the voltage of a current supplying capacitor. When the abnormal state is detected, the solenoid energizing time interval of the electromagnetic spill valve is elongated to advance the energizing time, thereby avoiding an engine stop state which may occur when a peak current cannot be supplied.
Although the Japanese Patent Publication Laid-open No.7-269404 and such can avoid the engine stop state caused by the faults of the control circuit of the electromagnetic spill valve, there has been a problem that the situation where a fault occurs in the electromagnetic spill valve per se to cause an abnormal revolution can not be avoided.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an electronic fuel injection apparatus comprising a control circuit of an electromagnetic spill valve for adjusting a fuel injection quantity in a distribution-type fuel injection pump for a diesel engine, and a computing unit for providing a command signal to the control circuit, in which a dangerous state is prevented beforehand when faults occur not only in the control circuit of the electromagnetic spill valve but also in the electromagnetic spill valve per se.
In order to achieve the above-mentioned object, an electronic fuel injection apparatus according to the present invention comprises a control circuit having, on either an inside or outside of the control circuit of an electromagnetic spill valve, means for detecting a driving current which flows through a solenoid of the spill valve, and means for detecting a delay point at which the driving current detected crosses a threshold value, and a computing unit having means for determining a state where a delay time interval from a transit point of the command signal to the delay point is equal to or more than a predetermined value as a slightly abnormal state to invalidate the command signal for a pilot injection.
Namely, in the present invention, the driving current which flows through the solenoid of the electromagnetic spill valve is detected, and the point (delay point) at which the driving current crosses (becomes equal to or more than, or equal to or less than) the threshold value is further detected. This may be executed on either the inside or outside of the control circuit.
The computing unit determines whether or not the delay time interval from the transit point (switchover point of ON/OFF) of the command signal to the delay point is equal to or more than a predetermined time.
As a result, recognizing that the delay time interval is equal to or more than the predetermined time, the computing unit determines the state as a slightly abnormal state to invalidate the command signal for the pilot injection.
Thus, when the electromagnetic spill valve per se or the control circuit thereof is in the slightly abnormal state, only the pilot injection which may be performed in advance of a main injection depending on the driving state of the engine is invalidated, so that what requires an instantaneous response is preliminarily avoided, whereby the fuel injection is more safely performed even when the electromagnetic spill valve is in such a slightly abnormal state.
It is to be noted that the means for detecting the delay point may be provided in the computing unit on the outside of the control circuit.
Furthermore, when it is determined that the above-mentioned delay time interval exceeds an allowable value larger than the above-mentioned predetermined value, the state is determined as a seriously abnormal state to stop the engine at present.
Thus, a very dangerous state, i.e. an abnormal raise of the engine revolution can be avoided beforehand.
It is preferable that when such an abnormal state is detected, a warning is given by using warning means.
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patent: 5697338 (1997-12-01), Hirose et al.
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patent: 10-302242 (1998-10-01), None
Iida Keiichi
Nishikawa Tomoo
Shioi Kenzo
Isuzu Motors Limited
Miller Carl S.
Staas & Halsey , LLP
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